Not Applicable
The present invention relates to a lighting fixture for projecting a beam of light and for use for spot lighting in connection with theater stages, cinema and television studios and the like, the fixture comprising:
a light source arranged at one end of a housing having a light beam exit aperture at the opposite end thereof, the light source and aperture being arranged generally concentric with a longitudinal or optical axis of the lighting fixture,
light beam influencing means at least comprising one or more, preferably four, beam-shaping blades and preferably also comprising other light influencing means such as one or more lenses and/or an iris and/or a pattern or gobo, for influencing a light beam emitted by the light source and being arranged along the path of the light beam along said longitudinal axis through the housing from the light source to the aperture, and
adjustment means for adjusting the position of at least said one or more beam-shaping blades and preferably of all said influencing means relative to said longitudinal axis.
The purpose of a lighting fixture as defined above is to produce a well-defined light beam or light cone with a geometry, angle of conicity and focal point that may be altered manually or by remote control.
A lighting fixture will normally comprise a light source, a reflector, a beam-shaping gate with beam-shaping blades, a pattern or gobo, an iris, a focusing lens, a zoom lens and a color filter as well as a suspension structure allowing the lighting fixture to be pivoted vertically and horizontally.
The visible part of the light emitted by the light source is collected by the reflector and is sent towards the iris, the gobo and the beam-shaping gate as a parallel light beam. The infrared part of the radiation from the light source passes through the dichroic coating of the reflector and impinges on the inner surface of the housing surrounding the light source, the heat being transported to the outer surface of the housing having cooling ribs for emitting the heat to the surrounding atmosphere.
It is often necessary to be able to determine the geometry of the light beam, and this is achieved by means of the zoom lens varying the angle of conicity of the light cone and by shaping or cutting off the periphery of the light beam by means of the beam-shaping gate with beam-shaping blades so as to obtain geometrical figures such as squares, triangles, trapezoids etc. The lenses project the light out through the aperture of the housing opposite the light source and through the color filter at the front end of the lighting fixture. It is important that the different elements influencing the shape and other characteristics of the light beam function as precisely as possible even when being influenced by the heat radiated from the light source and not removed by means of the dichroic reflector. This entails that the location and the configuration of the adjustment means for the beam-shaping blades, the gobo and iris are such that any bending caused by the heat influence from the light beam be kept at a minimum.
Lighting fixtures of this type are often arranged in places where it is difficult to access them manually and it is therefore of great importance that the adjustment means for adjusting the above-mentioned beam influencing means be as easily accessed and as flexible as possible when manual operation of the adjustment means is required.
U.S. Pat. No. 5,345,371 discloses a lighting fixture of the type in reference where the four beam-shaping blades or shutters are slidingly insertable in slots from outside, the shutters being radially adjustable by gripping a holder for each shutter and sliding the shutter in or relative to the optical axis. The shutters may also be tilted manually to a certain extent. However, a further tilting possibility is achieved by allowing the portion of the fixture containing the shutters to be rotated as a unit around the axis. This is a complicated solution and needs manual access to all holders of the shutters as well as manipulation of the rotation means for rotating part of the fixture. Motorization for remote control of this design will be very complicated and costly.
U.S. Pat. No. 4,890,208 discloses a lighting fixture of the type in reference where four shutters are arranged for motorized displacement radially toward the optical axis and motorized tilting by means of rack and pinion mechanisms. This solution is complicated and has only limited tilting capability, i.e. displacement capability circumferentially around the axis. Furthermore this solution is not well suited for manual operation.
It is an object of the invention to provide a lighting fixture of the type indicated, wherein access for manual operation is convenient and not dependent on the orientation of the lighting fixture, wherein motorization for remote control may be established in a simple and reliable manner and wherein the range of displacement circumferentially around the optical axis is as great as possible.
According to the invention this object is achieved by at least the adjustment means corresponding to said one or more beam-shaping blades and preferably all the adjustment means are arranged for rotation around said longitudinal axis and are connected to a respective influencing means such that rotation of the adjustment means around said longitudinal axis adjusts the position of the respective influencing means relative to said longitudinal axis.
Hereby the adjustment means may be accessed from practically any angle, and no limit to the adjustment possibilities in circumferential direction is inherent.
In the currently preferred embodiment the adjustment means comprise an annular body arranged with the axis thereof substantially coinciding with said longitudinal axis. This is a particularly simple and effective embodiment.
In the currently preferred embodiment of the invention the annular body comprises an outer rim configured for being engaged for applying rotational force thereto, the surface of said outer rim being provided with friction enhancing means such as roughening means, rubber surfacing, projections or teeth. Hereby manual and remote operation of the adjustment means is particularly simple and efficient.
Advantageously, the fixture further comprises one or more electrical motors connected to a respective drive wheel engaging said outer rim of a respective annular body for applying a rotational force thereto, and preferably the drive wheel is a gear having teeth, and the respective outer rim engaged by a respective gear is provided with teeth for meshing with the teeth of said gear when said gear rotates.
For use in remote control of the lighting fixture with pre-determined positions of the light influencing means, it is advantageous that the annular body be provided with a position indicating means for indicating the angular position of the annular body relative to said longitudinal axis. Hereby a reference point for the remote control operation is available, thereby eliminating errors and inaccuracies.
Advantageously, the position indicating means comprises an element that may be remotely sensed such as a magnet or a gap, and the fixture further comprises remote sensing means for sensing the angular position of said element relative to said longitudinal axis.
So as to obtain the greatest flexibility of adjustment and the greatest range of adjustment, the adjustment means for each of the one or more beam-shaping blades comprises radial adjustment means for adjusting the position of the blade radially relative to said axis, and circumferential adjustment means for adjusting the position of said blade circumferentially around said axis.
A particularly simple and efficient as well as accurate embodiment of the light fixture according to the invention is provided by the adjustment means for each of the one or more beam-shaping blades comprising two adjacent co-centrical annular bodies or rings each connected to one point of the blade such that relative rotation of the two rings alters the radial position of the blade.
In the currently preferred embodiment, the rings comprise guiding tracks recessed into the lateral surface of each ring facing the other ring, and each blade comprises a body extending generally transversely to said axis and two arms extending generally parallel to said axis, the arms each being provided with sliding connecting means for connecting the respective arm to each of the rings and being adapted for being slidingly received in a guiding track in each of said rings.